MySQL联合+限制

Question

这是我的问题

select PhoneNumber as _data,PhoneType as _type from contact_phonenumbers where ContactID = 3 and Type = 'R' and PT = 'M' 
union 
SELECT EmailID,Type  from contact_emails where ContactID = 3 and Type = 'P' 
UNION
SELECT EmailID,Type from contact_emails where ContactID = 3 and Type = 'O' 

在这里，我的问题是我只需要从每个select语句中提取一行。是否可以通过"limit“来获取它。

Answer 1

根据MySQL网站，您可以像这样对单个选择应用限制

(SELECT a FROM t1 WHERE a=10 AND B=1 ORDER BY a LIMIT 10)
UNION
(SELECT a FROM t2 WHERE a=11 AND B=2 ORDER BY a LIMIT 10);

http://dev.mysql.com/doc/refman/5.0/en/union.html